Prescription Stimulants and the Risk of Psychosis: A Systematic Review of Observational Studies

Comorbid ADHD and schizophrenia and the use of psychostimulants: a scoping review protocol

INTRODUCTION

Schizophrenia and attention deficit hyperactivity disorder (ADHD) are psychiatric disorders that have a profound impact on patients and healthcare systems globally. There is preliminary evidence suggesting a potential association between the two in terms of symptomatology and genetic underpinning. There is a paucity of guidance regarding pharmacological approaches for patients with comorbid ADHD and schizophrenia. There is a concern that psychostimulants may be more harmful than therapeutic. This scoping review protocol aims to systematically review the evidence for potential harm and benefit of psychostimulants among patients with comorbid ADHD and schizophrenia and identify research gaps.

METHODS AND ANALYSIS

This scoping review will employ a systematic and iterative approach to identify and synthesise the literature on the topic of psychostimulant use among patients with comorbid schizophrenia and ADHD, based on Arksey and O'Malley's framework. A search will be conducted in relevant databases, including MEDLINE (Ovid), Embase (Ovid), PsycINFO and ISI Web of Science. Additionally, grey literature will be sought. The scoping review will involve two independent reviewers screening the search results. The initial screen will be of title and abstract, and the subsequent full-text review will determine eligibility. A descriptive overview of the eligible studies will be provided. This scoping review has been registered at https://osf.io/cmn5s.

ETHICS AND DISSEMINATION

There is a paucity of high-quality evidence available to clinicians when making decisions regarding the prescription of psychostimulants to patients with comorbid schizophrenia and ADHD. To the best of our knowledge, this will be the first scoping review to examine the evidence addressing this clinical scenario. This review, therefore, has the potential to contribute to decision-making processes for this patient group, thereby improving patient outcomes. Furthermore, as this review is designed to identify research gaps, we aim to contribute to the development of a research agenda that will benefit patients, clinicians and healthcare systems. The dissemination strategy will involve open access peer review publication and scientific presentations.

Risk of Incident Psychosis and Mania With Prescription Amphetamines

OBJECTIVE

Amphetamine prescribing has increased in the United States in recent years. Previous research identified an increased risk of incident psychosis with prescription amphetamines. The purpose of this study was to examine the impact of dose levels of prescription amphetamines on the risk of this rare but serious adverse outcome.

METHODS

A case-control study using electronic health records was conducted to compare the odds of incident psychosis or mania with past-month exposure to prescription amphetamines. Case subjects were patients ages 16-35 hospitalized at McLean Hospital for incident psychosis or mania between 2005 and 2019. Control subjects were patients with an initial psychiatric hospitalization for other reasons, most commonly depression and/or anxiety. Amphetamine doses were converted to dextroamphetamine equivalents and divided into terciles. Secondary analyses evaluated the odds of psychosis or mania with methylphenidate use.

RESULTS

Among 1,374 case subjects and 2,748 control subjects, the odds of psychosis and mania were increased for individuals with past-month prescription amphetamine use compared with no use (adjusted odds ratio=2.68, 95% CI=1.90-3.77). A dose-response relationship was observed; high doses of amphetamines (>30 mg dextroamphetamine equivalents) were associated with 5.28-fold increased odds of psychosis or mania. Past-month methylphenidate use was not associated with increased odds of psychosis or mania compared with no use (adjusted odds ratio=0.91, 95% CI=0.54-1.55).

CONCLUSIONS

Although use of hospitalized control subjects excludes individuals with less severe disease, leading to selection bias, the study results suggest that caution should be exercised when prescribing high doses of amphetamines, with regular screening for symptoms of psychosis or mania.

Association between exposure to antidepressants and stimulants and age at onset of mania or psychosis: A retrospective population-based cohort study

This study investigated the impact of prior antidepressant and stimulant exposure on the age at onset (AAO) of first episode mania (FEM) or psychosis (FEP). Patients with FEP and FEM born after 1985 in Olmsted County, Minnesota, were identified using the Rochester Epidemiology Project. Duration and peak dose of antidepressant and stimulant exposure were quantified by review of the electronic health record. Peak doses were converted to defined daily dose (DDD), and cumulative exposure was calculated as DDD multiplied by treatment duration. Linear models were used to assess relationships between AAO with any exposures, and cumulative antidepressant and stimulant exposures. A total of 190 FEM/FEP patients (mean AAO=20.8 ± 3.7 years) were included. There was no significant difference in AAO with vs. without exposure to antidepressants or stimulants. Cumulative antidepressant exposure correlated with a later AAO in overall sample (r = 0.28, p < 0.001), and in FEP (r = 0.33, p < 0.001). No significant correlation emerged between cumulative stimulant exposure and AAO. Multivariable modeling confirmed that cumulative antidepressant exposure (Estimate=2.42, 95 %CI=1.66-3.18, p < 0.001), but not cumulative stimulant exposure (Estimate=-0.04, 95 %CI=-1.10-1.02, p = 0.94), was associated with later AAO. Antidepressant and stimulant exposures were not associated with earlier AAO. However, cumulative antidepressant exposure was associated with later AAO. Limitations include retrospective design and relatively small sample size. Our findings may inform adolescent treatment recommendations when assessing risk for psychotropic-related adverse events. Further risk modeling investigations of antidepressants and stimulants with larger sample sizes are needed to explore the role of antidepressant and stimulant exposure in the trajectory leading to FEM/FEP.

Potential therapeutics for effort-related motivational dysfunction: assessing novel atypical dopamine transport inhibitors

People with depression and other neuropsychiatric disorders can experience motivational dysfunctions such as fatigue and anergia, which involve reduced exertion of effort in goal-directed activity. To model effort-related motivational dysfunction, effort-based choice tasks can be used, in which rats can select between obtaining a preferred reinforcer by high exertion of effort vs. a low effort/less preferred option. Preclinical data indicate that dopamine transport (DAT) inhibitors can reverse pharmacologically-induced low-effort biases and increase selection of high-effort options in effort-based choice tasks. Although classical DAT blockers like cocaine can produce undesirable effects such as liability for misuse and psychotic reactions, not all DAT inhibitors have the same neurochemical profile. The current study characterized the effort-related effects of novel DAT inhibitors that are modafinil analogs and have a range of binding profiles and neurochemical actions (JJC8-088, JJC8-089, RDS3-094, and JJC8-091) by using two different effort-related choice behavior tasks in male Sprague-Dawley rats. JJC8-088, JJC8-089, and RDS3-094 significantly reversed the low-effort bias induced by the VMAT-2 inhibitor tetrabenazine, increasing selection of high-effort fixed ratio 5 lever pressing vs. chow intake. In addition, JJC8-089 reversed the effects of tetrabenazine in female rats. JJC8-088 and JJC8-089 also increased selection of high-effort progressive ratio responding in a choice task. However, JJC8-091 failed to produce these outcomes, potentially due to its unique pharmacological profile (i.e., binding to an occluded conformation of DAT). Assessment of a broad range of DAT inhibitors with different neurochemical characteristics may lead to the identification of compounds that are useful for treating motivational dysfunction in humans.

Treatment with psychostimulants and atomoxetine in people with psychotic disorders: reassessing the risk of clinical deterioration in a real-world setting

BACKGROUND

Although attention-deficit hyperactivity disorder (ADHD) is often comorbid with schizophrenia spectrum and other psychotic disorders (SZSPD), concerns about an increased risk of psychotic events have limited its treatment with either psychostimulants or atomoxetine.

AIMS

To examine whether the risk of hospital admission for psychosis in people with SZSPD was increased during the year following the introduction of such medications compared with the year before.

METHOD

This was a retrospective cohort study using Quebec (Canada) administrative health registries, including all Quebec residents with a public prescription drug insurance plan and a diagnosis of psychotic disorder, defined by relevant ICD-9 or ICD-10 codes, who initiated either methylphenidate, amphetamines or atomoxetine, between January 2010 and December 2016, in combination with antipsychotic medication. The primary outcome was time to hospital admission for psychosis within 1 year of initiation. State sequence analysis was also used to visualise admission trajectories for psychosis in the year following initiation of these medications, compared with the previous year.

RESULTS

Out of 2219 individuals, 1589 (71.6%) initiated methylphenidate, 339 (15.3%) amphetamines and 291 (13.1%) atomoxetine during the study period. After adjustment, the risk of hospital admission for psychosis was decreased during the 12 months following the introduction of these medications when used in combination with antipsychotics (adjusted HR = 0.36, 95% CI 0.24-0.54; P < 0.0001).

CONCLUSIONS

These findings suggest that, in a real-world setting, when used concurrently with antipsychotic medication, methylphenidate, amphetamines and atomoxetine may be safer than generally believed in individuals with psychotic disorders.

Differences in Patterns of Stimulant Use and Their Impact on First-Episode Psychosis Incidence: An Analysis of the EUGEI Study

BACKGROUND

Use of illegal stimulants is associated with an increased risk of psychotic disorder. However, the impact of stimulant use on odds of first-episode psychosis (FEP) remains unclear. Here, we aimed to describe the patterns of stimulant use and examine their impact on odds of FEP.

METHODS

We included patients with FEP aged 18-64 years who attended psychiatric services at 17 sites across 5 European countries and Brazil, and recruited controls representative of each local population (FEP = 1130; controls = 1497). Patterns of stimulant use were described. We computed fully adjusted logistic regression models (controlling for age, sex, ethnicity, cannabis use, and education level) to estimate their association with odds of FEP. Assuming causality, we calculated the population-attributable fractions for stimulant use associated with the odds for FEP.

FINDINGS

Prevalence of lifetime and recent stimulant use in the FEP sample were 14.50% and 7.88% and in controls 10.80% and 3.8%, respectively. Recent and lifetime stimulant use was associated with increased odds of FEP compared with abstainers [fully adjusted odds ratio 1.74,95% confidence interval (CI) 1.20-2.54, P = .004 and 1.62, 95% CI 1.25-2.09, P < .001, respectively]. According to PAFs, a substantial number of FEP cases (3.35% [95% CI 1.31-4.78] for recent use and 7.61% [95% CI 3.68-10.54] for lifetime use) could have been prevented if stimulants were no longer available and the odds of FEP and PAFs for lifetime and recent stimulant use varied across countries.

INTERPRETATION

Illegal stimulant use has a significant and clinically relevant influence on FEP incidence, with varying impacts across countries.